1. Field of the Invention
The present invention relates to diode circuits and, in particular, to integrated diode circuits.
2. Description of the Related Art
EP 1146567 A1 discloses a diode and a method of producing it. The diode is embodied as a pin diode and includes a heavily doped n-conducting silicon substrate onto which a lightly doped n-conducting region is deposited. A heavily doped p-conducting region is arranged on top of the lightly doped n-conducting region. The lightly doped region is formed by epitaxy on the heavily doped silicon substrate, wherein the heavily doped p-conducting region is produced by implantation in the epitaxy region. The pin diode formed in a circular shape in a plan view includes an insulation trench extending around the active diode structure and confining it. The diode is contacted by arranging an electrode on the heavily doped p-conducting region and by depositing, after back-side thinning, a back-side contact on the back surface of the heavily doped n-conducting silicon substrate. By providing the insulation trench, the extension of the depletion region and thus the area capacity of the diode are decoupled from the size of the upper electrode so that the extension of the depletion region can be chosen independently of the size of the electrode. This allows shorter switching on/off times which are particularly required when the pin diode is used as a high-frequency switch.
For installing such a diode into a circuit, it must be provided with an external HF coupling-in network and, additionally, with a bias feeding network so that it may be used in a high-frequency circuit. The semiconductor diode must thus be contacted externally to a high pass for the HF coupling-in, a high pass for the HF coupling-out and a low pass for the bias feed.
It is a disadvantage of this concept that the area consumption is relatively high. In addition, complicated and thus expensive processing steps are required in order to obtain a contacting of the external contacting, such as, for example, by bonding. In addition, the external contacting using bonding wires has the result that additional parasitic effects of which especially the inductivity of the bonding wires is problematic are introduced, which can, on the one hand, only be simulated and thus taken into consideration in the circuit design badly, and which, on the other hand, reduce the cutoff frequency of the entire circuit.